In many manufacturing and warehouse operations, it is conventional to move inventory and work in progress through the warehouse or factory on long conveyors. In such warehouses and factories, the conveyors are arranged to move parts down an assembly line so that the conveyor is adjacent a work table. Parts used to manufacture a particular object or completed objects can also be transported throughout a factory or warehouse by means of the conveyor system. Such conveyors are long and are typically fixed to the building floor or the like. The conveyors tend to divide a warehouse or factory into discrete areas so that traffic flow is somewhat inhibited. It is apparent that changes in the layout of a factory or warehouse cannot be readily accomplished since the conveyors are fixed to the building structure. Also, the conveyors take up space which could be used for the storage of goods or for additional work areas.
One desired feature in an assembly operation is to keep track of all of the parts in the system at one time. In some systems, a card reader and computer can be used to keep track of raw parts inventory, work in progress and finished goods. Accounting for the inventory depends upon human factors, that is, the assembler must keep all inventory control cards updated as he removes containers or objects from the conveyor line and replaces them with finished goods. Thus, there is a potential that the desired accuracy of such an inventory control system will not be achieved if the assembler fails to keep the cards updated.
It has been known to use an automatic conveying system for moving parts within a warehouse or factory. In such systems, a vehicle is moved about the work space either on a fixed rail or along some guide mechanism so as to transport containers and the like to desired locations in the factory or warehouse. One such example of an automated conveyor system is shown in the Hitomi et al U.S. Pat. No. 4,162,869 patent, issued July 31, 1979. The Hitomi et al patent discloses a conveying control system wherein an unmanned forklift vehicle is guided along leader cables. The vehicle mounts loading and unloading control means for detecting the presence or absence of a load at the vehicle, the number of layers in the load and instructions for conveying the load. The guidance system for the vehicle shown in the Hitomi et al patent requires that cables be buried in the floor of the building or the like which would made rearrangement of the factory layout difficult. Further, the vehicle used in the Hitomi et al system does not have any storage capacity so that only one container or pallet can be transported at a time.
Another type of a load transportation device is shown in the Anderson U.S. Pat. No. 4,010,856 patent, issued Mar. 8, 1977. The device shown in the Anderson patent includes a vertically moveable elevator having pivotally mounted conveyors which transfer a load to storage compartments. The elevator comprises a lifting means and a tilting mechanism which tilts the frame of the elevator so as to unload a unit onto the storage compartment. The vehicle which is used to transport parts is mounted on a track.
Still another warehouse system is shown in the Smith U.S. Pat. No. 4,010,855 patent, issued Mar. 8, 1977. The Smith warehouse system includes a plurality of stored pans and elevator platforms which engage a lip on each pan to pull a pan from a shelf. The platform includes a pair of chains which transfer a pan to and from the platform. This system would be useful in an automated warehousing operation.
The Oku U.S. Pat. No. 4,176,996 patent, issued Dec. 4, 1979, discloses another form of a storage system including a carriage moveable on guide rails positioned adjacent storage shelving. The carriage includes a scanning device which stops the carriage at a designated location in order to facilitate loading and unloading of the carriage.
While various systems have been proposed to move containers and the like through a warehouse or factory, the prior known systems have certain drawbacks. In this regard, some of the systems either require the use of a fixed rail or the like on which an unmanned vehicle is mounted. Such rails or buried cables would not allow for easy redesign of the factory or warehouse. Further, the vehicles used in these prior systems do not have the ability to pick up multiple containers from different locations and deliver them to several locations. Instead, the systems provide for the movement of a single container or package of containers from one point to a second location and do not contemplate the continuous loading and unloading of containers throughout a factory or warehouse such as occurs on an assembly line. It is desirable to provide such a system which allows for flexibility in a manufacturing operation wherein a vehicle can move parts, work in progress and finished goods from a storage area, through an assembly area and finally to a shipping area. It is further desirable to control such a system from a central location which could keep track of all of the parts in the system at any time. Finally, a system wherein a number of vehicles can be dispatched along a common path in order to perform the function of a conveyor system would provide for an efficient and continuous flow of parts through a factory or warehouse.